Bump build/metaschema-xslt from 04a4a4c to b63b373

Bumps [build/metaschema-xslt](https://github.com/usnistgov/metaschema-xslt) from `04a4a4c` to `b63b373`.
- [Commits](usnistgov/metaschema-xslt@04a4a4c...b63b373)

---
updated-dependencies:
- dependency-name: build/metaschema-xslt
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>